The human intervertebral disc is comprised of two major structures, an outer or peripheral tendinous structure, and an inner gelatinous nucleus pulposus located in a generally central region. Degeneration of the nucleus pulposus, which is typically associated with natural aging, may lead to disc degradation and loss of function.
Many patients experience chronic back pain caused by injury or age-related degeneration of an intervertebral disc. Current treatments range from bed rest to invasive surgical procedures, including discectomy, spinal fusion and total disc replacement.
Replacement or supplementation of the nucleus pulposus can relieve pain, restore healthy physiologic function to the disc and/or prevent additional wear or deterioration of the annulus. Currently, few minimally invasive techniques or materials exist for supplementation or replacement of the nucleus pulposus of a spinal disc into a selected site of a mammal. Even fewer techniques or materials provide the physiological/mechanical properties to restore the damaged disc to its full capacity.
Existing hydrogel technologies for supplementing or repairing the nucleus pulposus require the injection of pre-heated hydrogels through a large gauge needle into the intervertebral space. The resulting punctures may cause severe patient discomfort and provide an opening through which the resulting implant may be expelled. Thus, there is a need for hydrogels that permit injection via fine gauge needles (15 gauge and finer) while providing tissue implants that possess the required mechanical properties to support an intervertebral disc.